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Abstract:

A spatial light modulator includes a first transparent substrate; a
second transparent substrate; a phase modulation unit disposed between
the first transparent substrate and the second transparent substrate and
configured to modulate a phase of light passing through the phase
modulation unit by changing an optical path length of the phase
modulation unit according to a voltage applied to the phase modulation
unit; and an amplitude modulation unit disposed between the first
transparent substrate and the second transparent substrate and configured
to modulate an amplitude of light passing through the amplitude
modulation unit according to a voltage applied to the amplitude
modulation unit.

Claims:

1. A Spatial Light Modulator (SLM) comprising: a first transparent
substrate; a second transparent substrate; a phase modulation unit
disposed between the first transparent substrate and the second
transparent substrate and configured to modulate a phase of light passing
through the phase modulation unit by changing an optical path length of
the phase modulation unit according to a voltage applied to the phase
modulation unit; and an amplitude modulation unit disposed between the
first transparent substrate and the second transparent substrate and
configured to modulate an amplitude of light passing through the
amplitude modulation unit by changing a transmittance of the amplitude
modulation unit according to a voltage applied to the amplitude
modulation unit.

2. The SLM of claim 1, wherein the phase modulation unit comprises: a
first control electrode disposed on one of the first transparent
substrate and the second transparent substrate; and a phase modulation
layer configured to modulate the phase of the light passing through the
phase modulation unit by changing an optical path length of the phase
modulation layer according to a voltage applied to the phase modulation
layer via the first control electrode.

4. The SLM of claim 3, further comprising a protection layer disposed on
the polymer-dispersed liquid crystal layer to protect the
polymer-dispersed liquid crystal layer.

5. The SLM of claim 3, wherein the voltage applied to the phase
modulation layer via the first control electrode is higher than a
saturation voltage at which a transmittance of the phase modulation layer
is a maximum transmittance.

6. The SLM of claim 2, wherein the amplitude modulation unit comprises: a
second control electrode disposed on one of the first transparent
substrate and the second transparent substrate on which the first control
electrode is not disposed; and an amplitude modulation layer configured
to modulate the amplitude of the light passing through the amplitude
modulation unit by changing a transmittance of the amplitude modulation
layer according to a voltage applied to the amplitude modulation layer
via the second control electrode.

7. The SLM of claim 6, wherein the amplitude modulation layer comprises a
light shutter layer using an electrowetting phenomenon.

8. The SLM of claim 7, further comprising a common electrode disposed
between the phase modulation unit and the amplitude modulation unit.

9. The SLM of claim 6, further comprising a common electrode disposed
between the phase modulation unit and the amplitude modulation unit.

10. An optical apparatus comprising: the SLM of claim 1; and an image
sensing device or a light source; wherein if the optical apparatus
comprises the image sensing device, the optical apparatus is an image
acquisition device configured to acquire an image by sensing, using the
image sensing device, light of which a phase and an amplitude have been
modulated by the SLM of claim 1; and if the optical apparatus comprises
the light source, the optical apparatus is a 3-dimensional (3D) display
device configured to display a 3D image by modulating, using the SLM of
claim 1, a phase and an amplitude of light radiated from the light
source.

11. The optical apparatus of claim 10, wherein the phase modulation unit
comprises: a first control electrode disposed on one of the first
transparent substrate and the second transparent substrate; and a phase
modulation layer configured to modulate the phase of the light passing
through the phase modulation unit by changing an optical path length of
the phase modulation layer according to a voltage applied to the phase
modulation layer via the first control electrode.

13. The optical apparatus of claim 12, further comprising a protection
layer disposed on the polymer-dispersed liquid crystal layer to protect
the polymer-dispersed liquid crystal layer.

14. The optical apparatus of claim 12, wherein the voltage applied to the
phase modulation layer via the first control electrode is higher than a
saturation voltage at which a transmittance of the phase modulation layer
is a maximum transmittance.

15. The optical apparatus of claim 11, wherein the amplitude modulation
unit comprises: a second control electrode disposed on the one of the
first transparent substrate and the second transparent substrate on which
the first control electrode is not disposed; and an amplitude modulation
layer configured to modulate the amplitude of the light passing through
the amplitude modulation unit by changing a transmittance of the
amplitude modulation layer according to a voltage applied to the
amplitude modulation layer via the second control electrode.

17. The optical apparatus of claim 16, further comprising a common
electrode disposed between the phase modulation unit and the amplitude
modulation unit.

18. The optical apparatus of claim 15, further comprising a common
electrode disposed between the phase modulation unit and the amplitude
modulation unit.

19. A Spatial Light Modulator (SLM) comprising: a first transparent
substrate; a second transparent substrate; a phase modulation unit
disposed between the first transparent substrate and the second
transparent substrate and configured to modulate a phase of light passing
through the phase modulation unit without changing an amplitude of the
light passing through the phase modulation unit; and an amplitude
modulation unit disposed between the first transparent substrate and the
second transparent substrate and configured to modulate an amplitude of
light passing through the amplitude modulation unit without changing a
phase of the light passing through the amplitude modulation unit.

20. The SLM of claim 19, wherein the phase modulation unit and the
amplitude modulation unit are arranged so that light passing through any
portion of the SLM passes through both the phase modulation unit and the
amplitude modulation unit.

21. The SLM of claim 19, wherein one of the phase modulation unit and the
amplitude modulation unit comprises partitions dividing the SLM into
pixel or sub-pixel units.

22. The SLM of claim 19, wherein the phase modulation unit is further
configured to modulate the phase of the light passing through the phase
modulation unit without changing the amplitude of the light passing
through the phase modulation unit by changing only an optical path length
of the phase modulation unit according to a voltage applied to the phase
modulation unit without changing a transmittance of the phase modulation
unit according to the voltage applied to the phase modulation unit.

23. The SLM of claim 19, wherein the amplitude modulation unit is further
configured to modulate the amplitude of the light passing through the
amplitude modulation unit without changing the phase of the light passing
through the amplitude modulation unit by changing only a transmittance of
the amplitude modulation unit according to a voltage applied to the
amplitude modulation unit without changing an optical path length of the
amplitude modulation unit according to the voltage applied to the
amplitude modulation unit.

24. The SLM of claim 19, wherein the phase modulation unit comprises: a
first control electrode; and a phase modulation layer configured to
modulate the phase of the light passing through the phase modulation unit
by changing an optical path length of the phase modulation layer
according to a voltage applied to the first control electrode without
changing a transmittance of the phase modulation layer according to the
voltage applied to the first control electrode.

26. The SLM of claim 24, wherein the amplitude modulation unit comprises:
a second control electrode; and an amplitude modulation layer configured
to modulate the amplitude of the light passing through the amplitude
modulation unit by changing a transmittance of the amplitude modulation
layer according to a voltage applied to the second control electrode
without changing an optical path length of the amplitude modulation layer
according to the voltage applied to the second control electrode.

27. The SLM of claim 26, wherein the amplitude modulation layer comprises
a light shutter using an electrowetting phenomenon.

28. The SLM of claim 26, further comprising a common electrode disposed
between the phase modulation unit and the amplitude modulation unit;
wherein the phase modulation layer is disposed between the first control
electrode and the common electrode; and the amplitude modulation layer is
disposed between the second control electrode and the common electrode.

29. The SLM of claim 28, wherein the first control electrode is disposed
on a surface of the first transparent substrate facing the second
transparent substrate, and the second control electrode is disposed on a
surface of the second transparent substrate facing the first transparent;
or the first control electrode is disposed on the surface of the second
transparent substrate facing the first transparent substrate, and the
second control electrode is disposed on the surface of the first
transparent substrate facing the second transparent substrate.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Korean Patent Application
No. 10-2011-0072568 filed on Jul. 21, 2011, in the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by
reference in its entirety.

BACKGROUND

[0002] 1. Field

[0003] This disclosure relates to a spatial light modulator and an optical
apparatus employing the same.

[0004] 2. Description of the Related Art

[0005] A Spatial Light Modulator (SLM) is a device used to control a
distribution of light in optical systems. The SLM may be used, for
example, for holographic 3-dimensional (3D) displays, beam forming,
optical filtering, etc.

[0006] Light modulation is achieved by a combination of an amplitude
change and a phase change. Thus, not only phase modulation but also
amplitude modulation is necessary for the light modulation. However,
because most SLMs modulate only a phase or an amplitude of light, the use
of an SLM for modulating only a phase or an amplitude of light causes the
limit of an expression.

SUMMARY

[0007] According to an aspect, a Spatial Light Modulator (SLM) includes a
first transparent substrate; a second transparent substrate; a phase
modulation unit disposed between the first transparent substrate and the
second transparent substrate and configured to modulate a phase of light
passing through the phase modulation unit by changing an optical path
length of the phase modulation unit according to a voltage applied to the
phase modulation unit; and an amplitude modulation unit disposed between
the first transparent substrate and the second transparent substrate and
configured to modulate an amplitude of light passing through the
amplitude modulation unit by changing a transmittance of the amplitude
modulation unit according to a voltage applied to the amplitude
modulation unit.

[0008] The phase modulation unit may include a first control electrode
disposed on one of the first transparent substrate and the second
transparent substrate; and a phase modulation layer configured to
modulate the phase of the light passing through the phase modulation unit
by changing an optical path length of the phase modulation layer
according to a voltage applied to the phase modulation layer via the
first control electrode.

[0009] The phase modulation layer may include a polymer-dispersed liquid
crystal layer.

[0010] The SLM may further include a protection layer disposed on the
polymer-dispersed liquid crystal layer to protect the polymer-dispersed
liquid crystal layer.

[0011] The voltage applied to the phase modulation layer via the first
control electrode may be higher than a saturation voltage at which a
transmittance of the phase modulation layer is a maximum transmittance.

[0012] The amplitude modulation unit may include a second control
electrode disposed on one of the first transparent substrate and the
second transparent substrate on which the first control electrode is not
disposed; and an amplitude modulation layer configured to modulate the
amplitude of the light passing through the amplitude modulation unit by
changing a transmittance of the amplitude modulation layer according to a
voltage applied to the amplitude modulation layer via the second control
electrode.

[0013] The amplitude modulation layer may include a light shutter layer
using an electrowetting phenomenon.

[0014] The SLM may further include a common electrode disposed between the
phase modulation unit and the amplitude modulation unit.

[0015] According to an aspect, an optical apparatus include the SLM
described above; and an image sensing device or a light source; wherein
if the optical apparatus includes the image sensing device, the optical
apparatus is an image acquisition device configured to acquire an image
by sensing, using the image sensing device, light of which a phase and an
amplitude have been modulated by the SLM described above; and if the
optical apparatus includes the light source, the optical apparatus is a
3-dimensional (3D) display device configured to display a 3D image by
modulating, using the SLM described above, a phase and an amplitude of
light radiated from the light source.

[0016] According to an aspect, a Spatial Light Modulator (SLM) includes a
first transparent substrate; a second transparent substrate; a phase
modulation unit disposed between the first transparent substrate and the
second transparent substrate and configured to modulate a phase of light
passing through the phase modulation unit without changing an amplitude
of the light passing through the phase modulation unit; and an amplitude
modulation unit disposed between the first transparent substrate and the
second transparent substrate and configured to modulate an amplitude of
light passing through the amplitude modulation unit without changing a
phase of the light passing through the amplitude modulation unit.

[0017] The phase modulation unit and the amplitude modulation unit may be
arranged so that light passing through any portion of the SLM passes
through both the phase modulation unit and the amplitude modulation unit.

[0018] One of the phase modulation unit and the amplitude modulation unit
may include partitions dividing the SLM into pixel or sub-pixel units.

[0019] The phase modulation unit may be further configured to modulate the
phase of the light passing through the phase modulation unit without
changing the amplitude of the light passing through the phase modulation
unit by changing only an optical path length of the phase modulation unit
according to a voltage applied to the phase modulation unit without
changing a transmittance of the phase modulation unit according to the
voltage applied to the phase modulation unit.

[0020] The amplitude modulation unit may be further configured to modulate
the amplitude of the light passing through the amplitude modulation unit
without changing the phase of the light passing through the amplitude
modulation unit by changing only a transmittance of the amplitude
modulation unit according to a voltage applied to the amplitude
modulation unit without changing an optical path length of the amplitude
modulation unit according to the voltage applied to the amplitude
modulation unit.

[0021] The phase modulation unit may include a first control electrode;
and a phase modulation layer configured to modulate the phase of the
light passing through the phase modulation unit by changing an optical
path length of the phase modulation layer according to a voltage applied
to the first control electrode without changing a transmittance of the
phase modulation layer according to the voltage applied to the first
control electrode.

[0022] The phase modulation layer may include a polymer-dispersed liquid
crystal.

[0023] The amplitude modulation unit may include a second control
electrode; and an amplitude modulation layer configured to modulate the
amplitude of the light passing through the amplitude modulation unit by
changing a transmittance of the amplitude modulation layer according to a
voltage applied to the second control electrode without changing an
optical path length of the amplitude modulation layer according to the
voltage applied to the second control electrode.

[0024] The amplitude modulation layer may include a light shutter using an
electrowetting phenomenon.

[0025] The SLM may include a common electrode disposed between the phase
modulation unit and the amplitude modulation unit; the phase modulation
layer may be disposed between the first control electrode and the common
electrode; and the amplitude modulation layer may be disposed between the
second control electrode and the common electrode.

[0026] The first control electrode may be disposed on a surface of the
first transparent substrate facing the second transparent substrate, and
the second control electrode may be disposed on a surface of the second
transparent substrate facing the first transparent; or the first control
electrode may be disposed on the surface of the second transparent
substrate facing the first transparent substrate, and the second control
electrode may be disposed on the surface of the first transparent
substrate facing the second transparent substrate.

[0027] Additional aspects will be set forth in part in the description
that follows and, in part, will be apparent from the description, or may
be learned by practice of the described examples.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other aspects will become apparent and more readily
appreciated from the following description of examples, taken in
conjunction with the accompanying drawings in which:

[0029] FIG. 1 is a schematic cross-sectional diagram of a Spatial Light
Modulator (SLM) according to an example;

[0030] FIGS. 2A to 2C are schematic cross-sectional diagrams for
describing light dispersion, light transmission, and phase modulation
processes according to a magnitude of a voltage applied to the phase
modulation layer of FIG. 1;

[0031] FIGS. 3A and 3B are schematic cross-sectional diagrams for
describing an operation of the amplitude modulation unit of FIG. 1; and

[0032] FIG. 4 is a schematic diagram of an optical apparatus to which the
SLM of FIG. 1 is applied according to an example.

DETAILED DESCRIPTION

[0033] A light modulator and an optical apparatus employing the same
according to examples will now be described more fully with reference to
the accompanying drawings, in which examples are shown. In the drawings,
the widths and thicknesses of layers and regions may be exaggerated for
clarity. Like reference numerals refer to like elements throughout the
detailed description and the drawings.

[0034] FIG. 1 is a schematic cross-sectional diagram of a spatial light
modulator (SLM) 1 according to an example. Referring to FIG. 1, the SLM 1
includes first and second transparent substrates 10 and 11, and a phase
modulation unit 30 and an amplitude modulation unit 50 disposed between
the first and second transparent substrates 10 and 11.

[0035] In general, a glass substrate or a transparent plastic substrate
may be used as the first and second transparent substrates 10 and 11. The
first and second transparent substrates 10 and 11 may be the same type of
substrate, or may be different types of substrates.

[0036] The phase modulation unit 30 is formed to modulate a phase of light
passing therethrough by changing an optical path length of the phase
modulation unit according to a voltage applied to the phase modulation
unit 30. The phase modulation unit 30 includes a first control electrode
31 disposed on any one, e.g., the first transparent substrate 10 as shown
in FIG. 1, of the first and second transparent substrates 10 and 11, and
a phase modulation layer 32 for modulating a phase of light passing
therethrough by changing an optical path length of the phase modulation
layer 32 according to a voltage applied to the phase modulation layer 32
via the first control electrode 31. The phase modulation unit 30 may
further include a common electrode 39 that is commonly used by the
amplitude modulation unit 50. As shown in FIG. 1, the common electrode 39
may be disposed to face the first control electrode 31 on an opposite
surface of the phase modulation layer 32. The phase modulation unit 30
and the amplitude modulation unit 50 may be formed to use respective
electrodes instead of using the common electrode 39.

[0037] The first control electrode 31 and the common electrode 39 are
transparent electrodes and may be formed using, for example, a
transparent conductive inorganic material, such as Indium Tin Oxide (ITO)
or ZnO. A transparent conductive inorganic material or a transparent
conductive organic material may be used as the first control electrode
31. That is, the first control electrode 31 and the common electrode 39
may be formed using the same material or different materials.

[0038] In addition, the first control electrode 31 may be formed as
stripes, and the common electrode 39 may be formed as stripes crossing
the stripes of the first control electrode 31. Areas in which the stripes
of the first control electrode 31 and the stripes of the common electrode
39 cross each other may correspond to pixels or sub-pixels. The first
control electrode 31 and the common electrode 39 may be formed to have
different shapes. For example, the first control electrode 31 may be
formed to have a shape corresponding to each pixel or sub-pixel, and the
common electrode 39 may be formed to have a shape covering the entire
surface of the phase modulation unit 30.

[0039] The phase modulation layer 32 may include a polymer-dispersed
liquid crystal layer (PDLC) layer 33. The PDLC layer 33 may be produced
as a film by mixing a polymer 33a and a liquid crystal so that liquid
crystal droplets 33b are randomly dispersed in the polymer 33a. The PDLC
layer 33 may be formed by nematic liquid crystals and monomer of
bisphenol A dimethacrylate, 2-hydroxy-2-methyl-1-phenyl-1-propaneone.
Materials suitable for use in the PDLC layer 33 are well known to one of
ordinary skill in the art, and thus will not be described here. When the
phase modulation layer 32 is formed as a film, another component, e.g.,
the amplitude modulation unit 50, may be integrated on the phase
modulation layer 32, thereby simplifying the manufacturing of the SLM 1.

[0040] When the PDLC layer 33 is included in the phase modulation unit 30
as the phase modulation layer 32 as described above and no voltage is
applied to the PDLC layer 33 (V=0), or a voltage not high enough to start
to align the liquid crystal directors of the liquid crystal droplets 33b
with an electric field in the PDLC layer 33 is applied to the PDLC layer
33, i.e., a voltage that smaller than a threshold voltage of the PDLC
layer 33, as shown in FIG. 2A, the PDLC layer 33 disperses incident light
due to a difference between a refractive index of the polymer 33a and a
refractive index of the liquid crystal droplets 33b. V0 shown in
FIG. 2A denotes 0 V or a voltage lower than the threshold voltage
required to start to align the liquid crystal directors of the liquid
crystal droplets 33b with the electric field in the PDLC layer 33.

[0041] When a predetermined voltage V1 high enough to align the
liquid crystal directors of the liquid crystal droplets 33b with the
electric field in the PDLC layer 33 is applied to the PDLC layer 33, as
shown in FIG. 2B, thereby making the refractive index of the liquid
crystal of the liquid crystal droplets 33b almost the same as the
refractive index of the polymer 33a, incident light is transmitted
through the PDLC layer 33 without dispersion.

[0042] As shown in FIGS. 2A and 2B, the PDLC layer 33 acts as a light
shutter for allowing or blocking the transmission of light according to
whether a voltage applied to the PDLC layer 33 is V1 or V0.

[0043] When a saturation voltage higher than the predetermined voltage
V1 is applied to the PDLC layer 33, as shown in FIG. 2c, a
transmittance of the PDLC layer 33 becomes saturated. That is, a
transmittance of the PDLC layer reaches a maximum transmittance at the
saturation voltage that does not continue to increase even if a voltage V
applied to the PDLC layer 33 is increased above the saturation voltage.
When a voltage higher than the saturation voltage for saturating the
transmittance is applied to the PDLC layer 33, although the transmittance
remains constant, an entire refractive index of the polymer 33a and the
liquid crystal droplets 33b varies according to the voltage, and thus an
optical path length of the PDLC layer 33 varies according to the voltage.
For example, when V2 denotes the saturation voltage for saturating a
transmittance and is higher than the predetermined voltage V1, by
increasing a voltage V applied to the PDLC layer 33 to be higher than
V2, the optical path length of the PDLC layer 33 is changed
according to the voltage V even though the transmittance is saturated.
Since a change in optical patch length produces a change in phase, a
phase of light passing through the phase modulation unit 30 may be
modulated by adjusting a magnitude of a voltage applied to the PDLC layer
33. Accordingly, by modulating the phase of light by adjusting the
magnitude of a voltage applied to the PDLC layer 33 for each pixel or
sub-pixel, the SLM 1 may be operated as a phase SLM.

[0044] As described above, when the SLM 1 operates as a phase SLM, a
voltage applied to the phase modulation layer 32 via the first control
electrode 31 is a voltage higher than the saturation voltage V2 for
saturating a transmittance of the PDLC layer 33.

[0045] Since the PDLC layer 33 is used as the phase modulation layer 32 of
the SLM 1, because a phase is determined by an average refractive index
obtained from the refractive index of the liquid crystal of the liquid
crystal droplets 33b and the refractive index of the polymer 33a, the use
of a polarizer is unnecessary, unlike in conventional SLMs using a
general liquid crystal, so the light efficiency of the SLM 1 is higher
than conventional SLMs. In addition, because the SLM 1 is used only under
a condition in which the transmittance of the PDLC layer 33 is a maximum
transmittance and does not change, the PDLC layer 33 may modulate only a
phase of light.

[0046] Referring back to FIG. 1, the SLM 1 further includes a protection
layer 37 for protecting the PDLC layer 33 disposed on the PDLC layer 33.
However, the protection layer 37 may be omitted.

[0047] The amplitude modulation unit 50 is formed to modulate an amplitude
of light by changing a transmittance of the amplitude modulation unit 50
according to a voltage applied thereto.

[0048] The amplitude modulation unit 50 includes a second control
electrode 51 disposed on an inner surface of the other one, e.g., the
second transparent substrate 11, of the first and second transparent
substrates 10 and 11 on which the first transparent electrode 31 is not
disposed, and an amplitude modulation layer 53 for modulating an
amplitude of light by adjusting a transmittance of the amplitude
modulation layer according to a voltage applied to the amplitude
modulation layer 53 through the second control electrode 51. The
amplitude modulation unit 50 may further include the common electrode 39
described above.

[0049] The second electrode 51 may be disposed to face the common
electrode 39 on an opposite surface of the amplitude modulation layer 53.
Similar to the first control electrode 31 and the common electrode 39,
the second control electrode 51 is a transparent electrode and may be
formed using, for example, a transparent conductive inorganic material,
such as ITO or ZnO. A transparent conductive inorganic material or a
transparent conductive organic material may be used as the second control
electrode 51. The second control electrode 51 and the common electrode 39
may be formed using the same material or different materials.

[0050] A relationship between the second control electrode 51 and the
common electrode 39 may be the same as that between the first control
electrode 31 and the common electrode 39. That is, the second control
electrode 51 may be formed as stripes. When the common electrode 39 is
formed in stripes crossing the stripes of the first control electrode 31
as described above, the second control electrode 51 may be formed as
stripes crossing the stripes of the common electrode 39 and parallel to
the stripes of the first control electrode 31. Thus, when the common
electrode 39 formed as stripes is commonly used, the first control
electrode 31 and the second control electrode 51 may be formed in
substantially the same shape. Areas in which the stripes of the second
control electrode 51 and the stripes of the common electrode 39 cross
each other may correspond to pixels or sub-pixels. The second control
electrode 51 and the common electrode 39 may be formed to have different
shapes. For example, the second control electrode 51 may be formed to
have a shape corresponding to each pixel or sub-pixel, and the common
electrode 39 may be formed to have a shape covering the entire surface of
the amplitude modulation unit 50.

[0051] Although the phase modulation unit 30 and the amplitude modulation
unit 50 share the common electrode 39 in FIG. 1, this is only an example,
and the phase modulation unit 30 and the amplitude modulation unit 50 may
include separate electrodes instead of the common electrode 39. In
addition, although the first control electrode 31 and the second control
electrode 51 are disposed on the inner surfaces of the first and second
transparent substrates 10 and 11 in FIG. 1, respectively, if the separate
electrodes are included in the phase modulation unit 30 and the amplitude
modulation unit 50 instead of the common electrode 39, the separate
electrodes may be disposed on the inner surfaces of the first and second
transparent substrates 10 and 11, and the first control electrode 31 and
the second control electrode 51 may be disposed between the phase
modulation layer 32 and the amplitude modulation layer 53. In addition,
although the SLM 1 in FIG. 1 is formed in an order of the first
transparent substrate 10, the phase modulation unit 30, the amplitude
modulation unit 50, and the second transparent substrate 11, this is only
an example, and positions of the phase modulation unit 30 and the
amplitude modulation unit 50 may be exchanged with each other. As will be
apparent to one of ordinary skill in the art, other modifications may be
made to the structure of the SLM 1 in addition to the modifications
described above.

[0052] The amplitude modulation layer 53 modulates an amplitude of light
passing through the amplitude modulation unit 50 by changing only a
transmittance of the amplitude modulation layer 53 according to a voltage
applied thereto without changing a phase of the light passing through the
amplitude modulation unit 50, and includes, for example, a light shutter
layer using an electrowetting phenomenon.

[0053] That is, the amplitude modulation layer 53 consists of a solution
including a transparent aqueous solution 55 and an organic solution 57
that is opaque filled in a space between the second control electrode 51
and the common electrode 39. Distilled water or an aqueous solution in
which an electrolyte is dissolved may be used as the aqueous solution 55.
The organic solution 57 has a hydrophobic property exhibiting the
electrowetting phenomenon. Since the organic solution 57 is opaque and
therefore is able to block all of incident red (R) light, green (G)
light, and blue (B) light, the organic solution 57 includes an inorganic
or organic material for blocking the red (R) light, green (G) light, and
blue (B) light. An example of the inorganic material is carbon black, and
examples of the organic material are an organic dye and an organic
pigment. Black oil, for example, may be used as the organic solution 57.
Black ink may be used as the black oil, and may include carbon black. The
organic solution 57 may further include color filter materials currently
used in Liquid Crystal Displays (LCDs), such as red (R), green (G), and
blue (B) filter materials, dissolved in a transparent organic substance
such as an oil to provide color filters in respective pixels or
sub-pixels.

[0054] The entire surface of the common electrode 39 facing the amplitude
modulation layer 53 is processed to have a hydrophobic property. For
example, the entire surface of the common electrode 39 facing the
amplitude modulation layer 53 may be coated with a hydrophobic polymer.
Alternatively, a dielectric layer (not shown) having a hydrophobic
property may be disposed on the entire surface of the common electrode 39
facing the amplitude modulation layer 53. The dielectric layer consists
of one or more transparent materials, and is formed so that a surface of
the dielectric layer has a hydrophobic property. For example, the
dielectric layer may include a fluoropolymer or Parylene as an organic
material, and silicon dioxide (SiO2) or Barium Strontium Titanate
(BST) as an inorganic material. When the dielectric layer includes a
layer of SiO2 or BST disposed on the entire surface of the common
electrode 39 facing the amplitude modulation layer 53, the organic
material, e.g., a fluoropolymer or Parylene, is coated on a surface of
the dielectric layer facing the amplitude modulation layer 53 to provide
a sufficient hydrophobic property to the surface of the dielectric layer
facing the amplitude modulation layer 53.

[0055] Although a case where hydrophobic processing is performed on the
entire surface of the common electrode 39 facing the amplitude modulation
layer 53, or a dielectric layer having a hydrophobic property is disposed
on the entire surface of the common electrode 39 facing the amplitude
modulation layer 53 has been described, hydrophobic processing may be
performed on the entire surface of the second control electrode 51 facing
the amplitude modulation layer 53, or a dielectric layer having a
hydrophobic property may be disposed on the entire surface of the second
control electrode 51 facing the amplitude modulation layer 53, or
hydrophobic processing may be performed on the entire surface of both the
common electrode 39 and the second control electrode 51 facing the
amplitude modulation layer 53, or a dielectric layer having a hydrophobic
property may be disposed on the entire surface of both the common
electrode 39 and the second control electrode 51 facing the amplitude
modulation layer 53. In the description of FIG. 1 and below, a case where
hydrophobic processing is performed on the entire surface of the common
electrode 39 facing the amplitude modulation layer 53 is described.

[0056] A plurality of partitions 59 are disposed in an area between the
first and second transparent substrates 10 and 11 in which the amplitude
modulation layer 53 is formed. These partitions 59 maintain a constant
distance between the first and second transparent substrates 10 and 11,
enable the amplitude modulation layer 53 in which a solution is filled to
be formed, and partition the amplitude modulation layer 53 in which a
solution is filled into compartments respectively corresponding to pixels
or sub-pixels. The plurality of partitions 59 are disposed between
segments of the second control electrode 51 respectively corresponding to
pixels or sub-pixels.

[0057] In the amplitude modulation unit 50 having the structure described
above, i.e., the light shutter using the electrowetting phenomenon, when
a predetermined voltage is applied between the second control electrode
51 and the common electrode 39, the hydrophobic surface of the common
electrode 39 (or the dielectric layer in a case where the dielectric
layer is disposed on the common electrode 59) is changed to have a
hydrophilic property. Accordingly, an area in which the aqueous solution
55 contacts the surface of the common electrode 39 increases, and the
organic solution 57 moves towards edges of each pixel or sub-pixel, i.e.,
towards each partition 59, thereby increasing an area through which light
passes, thereby increasing an amount of light passing through the
amplitude modulation layer 53, thereby increasing a transmittance of the
amplitude modulation layer 53.

[0058] FIGS. 3A and 3B are schematic cross-sectional diagrams for
describing an operation of the amplitude modulation unit 50. FIG. 3A
shows a state in which no voltage is applied between the second control
electrode 51 and the common electrode 39, and FIG. 3B shows a state in
which a predetermined voltage is applied between the second control
electrode 51 and the common electrode 39.

[0059] Referring to FIG. 3A, when no voltage is applied between the second
control electrode 51 and the common electrode 39, because a sum of an
interface energy between the organic solution 57 and the aqueous solution
55 and an interface energy between the organic solution 57 and the
surface of the common electrode 39 having a hydrophobic property
(hereinafter referred to as "the hydrophobic surface") is less than an
interface energy between the aqueous solution 55 and the hydrophobic
surface, the organic solution 57 covers the entire hydrophobic surface,
and the aqueous solution 55 is disposed on the organic solution 57.
Accordingly, incident light is blocked by the organic solution 57 that is
opaque so that the incident light is not transmitted through the
amplitude modulation layer 53.

[0060] Referring to FIG. 3B, if a predetermined voltage is applied between
the second control electrode 51 and the common electrode 39, a contact
characteristic between the hydrophobic surface and the organic solution
57 is changed. For example, the hydrophobic surface is changed to a
hydrophilic surface, and accordingly an area in which the aqueous
solution 55 contacts the hydrophilic surface increases. Therefore, the
organic solution 57 moves towards areas to which the predetermined
voltage is not applied, i.e., towards each partition 59. As a result,
because incident light is transmitted through the transparent aqueous
solution 55 in each pixel or sub-pixel, the incident light is transmitted
through the amplitude modulation layer 53. When a hydrophilic
characteristic of the surface of the common electrode 39 increases by
increasing a voltage applied between the second control electrode 51 and
the common electrode 39 within a predetermined range, the area in which
the aqueous solution 55 contacts the hydrophilic surface increases even
more, thereby increasing an amount of the incident light that is
transmitted through the amplitude modulation layer 53, therefore
increasing a transmittance of the amplitude modulation layer 53. Thus,
the transmittance of the amplitude modulate layer 53 changes according to
the voltage applied between the second control electrode 51 and the
common electrode 39.

[0061] Thus, an amount of light passing through the amplitude modulation
layer 53 may be modulated by changing a magnitude of a voltage applied
between the second control electrode 51 and the common electrode 39 to
change a transmittance of the amplitude modulation layer 53.

[0062] The SLM 1, which is a device capable of separately adjusting an
amplitude and a phase of light, i.e., a device that is a hybrid of a
phase SLM and an amplitude SLM in a single body, may be implemented by
integrating the phase modulation layer 32, such as the PDLC layer 33,
which is a phase SLM that changes only a phase of light without changing
an amplitude of light, with the amplitude modulation layer 53, e.g., the
light shutter using the electrowetting phenomenon, which is an amplitude
SLM that changes only an amplitude of light without changing a phase of
light, and may be control light in pixel or sub-pixel units.

[0063] Because the phase SLM and the amplitude SLM of the SLM 1 can be
integrated in an integration process, an additional operation of aligning
the phase SLM with the amplitude SLM is not required when manufacturing
the SLM 1, and because the phase SLM controls only a phase of light and
the amplitude SLM controls only an amplitude of light, there is no
interference between the phase SLM and the amplitude SLM. In addition,
because a distance between the phase SLM and the amplitude SLM may be
reduced by using a film protection layer such as the protection layer 37,
crosstalk between adjacent pixels or subpixels due to divergence of light
in the SLM 1 may be minimized.

[0064] FIG. 4 is a schematic diagram of an optical apparatus to which the
SLM 1 is applied according to an example. Referring to FIG. 4, the
optical apparatus to which the SLM 1 is applied may be an image
acquisition apparatus, e.g., a camera, for acquiring an image by sensing,
using an image pickup device 3, light of which a phase and an amplitude
of light have been modulated by the SLM 1, or a 3D display device for
displaying a 3D image by modulating, using the SLM 1, a phase and an
amplitude of light radiated from a light source 5 (the light source 5 may
be an external light source or a backlight unit).

[0065] As described above, according to the examples, an SLM is
implemented as a single hybrid structure in which a phase light modulator
and an amplitude light modulator are formed on a substrate in a structure
in which a phase modulation unit and an amplitude modulation unit are
layered.

[0066] While this disclosure has been particularly shown and described
with reference to examples thereof, it will be understood by those
skilled in the art that various changes in form and details may be made
in these examples without departing from the spirit and scope of the
invention as defined by the claims and their equivalents. It should be
understood that the examples described herein should be considered in a
descriptive sense only, and not for purposes of limitation. Descriptions
of features or aspects in each example are to be considered as being
applicable to similar features or aspects in other examples. Suitable
results may be achieved if the described techniques are performed in a
different order and/or if components in a described system, architecture,
device, or circuit are combined in a different manner and/or replaced or
supplemented by other components or their equivalents. Therefore, the
scope of the invention is defined not by the detailed description of the
disclosure, but by the claims and their equivalents, and all variations
within the scope of the claims and their equivalents are to be construed
as being included in the invention.